In the field of signal processing, there is a need to perform complex multiplications on signal samples; that is, an incoming signal sample may be in the form of a binary digital word having a primary group of binary bits corresponding to the real component of a complex number, and having a secondary group of binary bits corresponding to the imaginary component of a complex number. A complex number is a number having a real component and an imaginary component. The complex number is, by convention, considered a quantity which may be expressed as components in two-dimensional space in the direction of a pair of basis vectors. Basis vectors are vectors of unit length in a two dimensional space which may or may not be referred to and symbolically operated upon as a complex number. For example, a signal sample may be considered as a vector which is represented by a complex number with a first component corresponding to the amplitude of the signal sample, and a second component corresponding to the phase of the signal sample. This vector may also be expressed in components which have been conventionally resolved to lie on the real and the imaginary axes or more generally as components along any pair of non-colinear axes. Filtering and other signal processing operations may be performed on the incoming signal samples by a complex multiplier which performs the operation corresponding to multiplication of complex numbers.
A prior art complex multiplier is disclosed in detail in the description accompanying FIG. 1.